Unmanned aerial vehicle collision avoidance system

ABSTRACT

A system for collision avoidance includes memory storing instructions which, when executed, cause one or more processors to perform determining a direction of flight of a first drone, causing broadcasting, in the direction of flight based, a beamformed signal of beacon frames, determining a new flight direction of the same first drone, in response to the new flight direction, causing broadcasting of the beacon frames in the new flight direction, detecting second beacon frames from a second drone associated with a direction from which the second beacon frames are arriving; in response, causing the first drone to perform, without input from a pilot, one or more of a change in elevation, heading, speed, or type of operation, directed toward causing the first drone to follow a flight path that is separated from the second drone.

TECHNICAL FIELD

The present disclosure generally relates to improved methods, computersoftware and/or computer hardware in the field of unmanned aerialvehicle (UAV) apparatus or drones. The disclosure relates morespecifically to improved computer-implemented methods for detecting andavoiding collisions among drones.

BACKGROUND

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not prior art to the claims in this application andare not admitted to be prior art by inclusion in this section.

Drones are becoming ever more popular. Hobbyist pilots may be foundflying drones in backyards, parks, and other places. Commercial uses fordrones are also being explored. In high density areas, where multipledrones may be flying and/or sharing the same airspace, collisions arebecoming more common. Collisions may occur due to pilot error, poorvisibility, or many other reasons. Since drones are costly devices, andcollisions typically cause significant damage, and may even pose dangerto those nearby, improved methods of collision detection and avoidanceare needed.

SUMMARY

The appended claims may serve as a summary of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a block diagram of a system in accordance with anembodiment of the invention.

FIG. 2 shows a flowchart of a method in accordance with an embodiment ofthe invention.

FIG. 3 shows a flowchart of a method in accordance with an embodiment ofthe invention.

FIG. 4 shows an example in accordance with an embodiment of theinvention.

FIG. 5 shows a block diagram of a computer system with which anembodiment of the invention may be implemented.

DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however,that the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring thepresent invention. Embodiments are described in sections according tothe following outline:

1. OVERVIEW

2. EXAMPLE SYSTEM IMPLEMENTATION

3. FIRST FUNCTIONAL EXAMPLE

4. SECOND FUNCTIONAL EXAMPLE

5. IMPLEMENTATION EXAMPLE

6. HARDWARE OVERVIEW

1. Overview

Computer-implemented techniques are provided for detecting and avoidingcollisions between drones. In one embodiment, using a computer,application program, and radio frequency transceiver, digital beaconframes are broadcast wirelessly in the flight direction of a first droneand, if a second drone with compatible equipment detects the beaconframes, then the second drone generates a warning that the first droneis near, and the second drone may take evasive action such as changingheading, speed, elevation or any combination of these. For purposes ofthis disclosure, the terms “UAV” and “drone” are consideredinterchangeable.

In one embodiment, a drone operated by a pilot comprises multiple-inputand multiple-output (MIMO) antennas, an electronic digital memory unitand one or more digital processors that are configured to executeinstructions that are stored in the memory unit and programmed toperform: determining a flight direction; broadcasting, on a radiofrequency, a beamformed signal comprising a plurality of beacon framesin the flight direction; determining a new flight direction; in responseto the new flight direction, changing the broadcasting of the pluralityof beacon frames to the new flight direction; detecting one or morebeacon frames from a second drone, wherein the one or more beacon framesarrive from a direction; in response to detecting the one or more beaconframes, performing, without input from the pilot and based on thedirection, an evasive action to avoid the second drone.

Other aspects, features and embodiments will become apparent from thedisclosure as a whole.

2. Example System Implementation

FIG. 1 illustrates an example computer system in which the techniquesdescribed may be practiced, according to some embodiments. In oneembodiment, a computer system 100 comprises components that areimplemented at least partially by hardware at one or more computingdevices, such as one or more hardware processors executing storedprogram instructions stored in one or more memories for performing thefunctions that are described herein. In other words, all functionsdescribed herein are intended to indicate operations that are performedusing programming in a special-purpose computer or general-purposecomputer, in various embodiments. Computer system 100 illustrates onlyone of many possible arrangements of components configured to executethe programming described herein. Other arrangements may include feweror different components, and the division of work between the componentsmay vary depending on the arrangement.

Computer system 100 may be integrated into or hosted using a drone 105,and may be coupled to transceivers that are configured to send andreceive data using multiple-input and multiple-output (MIMO) antennas110. The computer system 100 may execute a collision avoidanceapplication 115 that is programmed to perform the functions that aredescribed further herein in other sections. The drone 105 may operateunder control of a remote controller 120.

Drone 105 is any drone or UAV, such as a recreational drone for hobbyistuse, a commercial drone for professional use, police drone, militarydrone, and/or a custom built drone. Drone 105 may be of any size and anytype of craft, such as a helicopter, quadcopter, or plane. Drone 105includes MIMO antennas 110 and a collision avoidance application 115.

Computer system 100 may also include many other elements that are notshown in FIG. 1, such as a central processing unit or microcontroller, ahard drive, memory, or other storage device. Drone 105 may include otherelements such as engines, propellers, flight control elements, cameras,and sensing devices including, but not limited to: gyroscope,accelerometer, compass, altimeter, Global Position System (GPS)receiver, airspeed (pitot) sensor and thermometers.

In an embodiment, drone 105 is controlled by a pilot via the remotecontroller 120. Remote controller 120 may be a radio with input/outputdevices, a computer, smartphone, handheld remote control, or any otherdevice capable of controlling a drone directly or indirectly via radio,satellite or other wireless telecommunication links. Remote controller120 may be any distance from drone 105 that the controller supportswithin range of wireless or satellite communication links. For example,if remote controller 120 is a handheld remote control, then remotecontroller 120 may be in visual range of drone 105, so that the humanpilot may see drone 105 and direct the drone appropriately.Alternatively, remote controller 120 may be miles away from drone 105.Remote controller 120 may include elements not shown in FIG. 1, such asa processor, memory, force feedback components, antennas, display, andvarious inputs. Remote controller 120 may send commands to, andcommunicate with, drone 105 using any method or frequency, such as Wi-Fior other radio signals, or satellite signals. Optionally, in anembodiment, remote controller 120 may execute a collision avoidanceapplication and send instructions to drone 105, instead of or inaddition to the collision avoidance application executing on computersystem 100. If the collision avoidance application executes on remotecontroller 120, additional data would be transmitted using thecommunication link between drone 105 and remote controller 120, and anyof the functionality discussed below in regards to collision avoidanceapplication 115 may be implemented on remote controller 120.

In an embodiment, MIMO antennas 110 comprise a three-dimensional networkof antennas mounted on drone 105. MIMO antennas 110 are configured toprovide transmission and receiving across a virtual sphere centered ondrone 105, so that signals may be sent and/or received from alldirections. In this configuration the MIMO antennas 110 are said toprovide spherical coverage of the drone 105. Any number of antennas maymake up MIMO antennas 110.

In an embodiment, MIMO antennas 110, in conjunction with other elementsof FIG. 1, are configured to send radio signals using beamforming.Beamforming is a form of directional signal transmission. Specifically,as discussed below, MIMO antennas 110 send beacon frames usingbeamforming so that the beacon frames are transmitted in the directionthat the drone 105 is flying at the time of the transmission. Likewise,MIMO antennas 110, in conjunction with other elements of FIG. 1, areable to receive beacon frames that were sent using beamforming fromanother source such as a second drone, and the direction and/or strengthof the received beacon frames may be detected or otherwise determined.The antennas that make up MIMO antennas 110 may be of any type, and maybe positioned on drone 105 in any suitable configuration. Anybeamforming technique may be used, such as those used in 802.11ac and/orin Active Electronically Scanned Array Antennas.

In an embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to generate and broadcastbeacon frames in a flight direction and to perform the other functionsthat are described herein in connection with certain flow diagrams.

In contrast to the methods described herein, in conventional practice,beacon frames are one of the management frames that may be used inwireless local area networks that conform to standard 802.11 of theInstitute of Electrical and Electronics Engineers (IEEE). Typicallybeacon frames are used to periodically advertise that a wireless networkis available for connection. Various information may be included in thebeacon frames, such as an identifier of the network (SSID) or networksetting information. Typically, an access point, or other networkelement, sends beacon frames at predefined intervals.

In an embodiment, unlike prior practice, the collision avoidanceapplication 115 uses beacon frames to efficiently warn other nearbydrones that drone 105 is nearby and inform the other drones of thedirection from which drone 105 is coming. The beacon frames broadcast bydrone 105 may be detected using compatible software and transceivers inanother drone or aircraft and, in response to detection, a change inheading or elevation can be made, or evasive action can be taken beforethe physical mass of the drone 105 collides with the other drone oraircraft. Further, using the beacon frames, the other drone or aircraftcan determine what direction and/or speed the drone 105 is traveling.

In an embodiment, collision avoidance application 115 may broadcastbeacon frames periodically and any time interval may be used. Theinterval may change dynamically based on the speed at which drone 105 istraveling, the amount of other drones in the area, or any other suitablefactor. Alternatively, collision avoidance application 115 may broadcastbeacon frames at a constant interval.

The beacon frames may be broadcast using any frequency including, butnot limited to: 900 MHz, 2.4 GHz, 3.6 GHz, 5 GHz, and/or 60 GHz. AnyIndustrial Scientific Medical (ISM) band and any communication standardmay be used to broadcast beacon frames, and the invention should not belimited to the above examples. Although any 802.11 standard may be used(or other standard), 802.11ac or other more recent standards within the802.11 family may be more suitable. Additionally, any other types ofradio networks may be used to broadcast beacon frames including, but notlimited to: 3G, 4G, 5G, etc.

Collision avoidance application 115 may generate beacon frames in anysuitable manner. When collision avoidance application 115 generatesbeacon frames, custom data elements may be included in the body, orother portions of the beacon frame. For example, a field may be includedto: identify the drone sending the beacon frame, indicate that thebeacon frame is being used for collision detection/avoidance, providedirection, speed, height, or other data relevant to the flight directionof drone 105, identify the drone sending the beacon frame as a specialtype, or any other data. Optionally, data from the beacon frames may beused to establish a wireless connection between two drones and transmitadditional, more detailed, data using the now-established wirelessconnection. Collision avoidance application 115 broadcasts the beaconframes using beamforming.

Collision avoidance application 115 and MIMO antennas 110 may performdirectional signal transmission using beamforming in any manner nowknown or later developed. Collision avoidance application 115 usesbeamforming to broadcast the beacon frames in the current flightdirection of drone 105. By using beamforming when broadcasting thebeacon frames, collision avoidance application 115 ensures that onlyother drones in or close to the current flight path of drone 105 receivethe beacon frames. Thus, when another drone receives/detects beaconframes, that drone is warned of an imminent collision, and may reactaccordingly. Further, reflection of radio-frequency energy is notrequired, as with radar. Instead, the drone 105 broadcasting the beaconframes may be unaware of which, if any, drones receive the beaconframes. Collision avoidance application 115 and MIMO antennas 110 mayperform beamforming using any technique.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to determine a flightdirection of drone 105. Collision avoidance application 115 maydetermine the flight direction of drone 105 based on commands receivedfrom remote controller 120. Alternatively, collision avoidanceapplication 115 may use input from sensors of drone 105, such as agyroscope, accelerometer, compass, altimeter, or a GPS receiver,individually or in combination. The flight direction is constantlyupdated at any suitable interval. The update interval may change basedon the speed, height, or other aspects of the current flight path ofdrone 105. Optionally, in addition to determining a flight direction, aflight speed is also determined. By also determining a speed, collisionavoidance application 115 is able to detect when drone 105 is hovering.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to cease broadcastingbeacon frames in response to drone 105 hovering or flying below athreshold speed. The threshold speed may be any amount, and may be setand/or adjusted by any party. By not broadcasting beacon frames whenhovering or below a threshold speed, collision avoidance application 115can reduce energy consumption and avoid needlessly warning other drones.Upon detecting that the drone 105 has begun flight again, or exceededthe speed threshold, broadcasting of beacon frames in the flightdirection is resumed.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to detect beacon framesfrom other drones, and determine a direction that the received beaconframes arrived from. The beacon frames are received from any directionusing MIMO antennas 110 to cover a spherical detection area around drone105. Within the detection area, beacon frames from other drones aredetectable. Upon receiving a beacon frame, collision avoidanceapplication 115 determines a direction from which the beacon frame wasreceived using any suitable method. For example, collision avoidanceapplication 115 may use the signal strength or other factors associatedwith the transmission to determine a direction. Alternatively, thedirection may be encoded in the beacon frames themselves. The directionmay be encoded as a full 3D vector, or any other suitable format. Once adirection from which beacon frames are received is known, evasive actionmay be taken to avoid a collision.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to perform evasiveactions. The evasive actions may be based on the direction from whichbeacon frames were received, current flight information of the dronereceiving the beacon frames (such as altitude, speed, heading, orothers), the frequency at which the beacon frames were received,information contained within the beacon frames, or any other suitableelement. Although drone 105 is controlled by a human pilot, the evasiveactions that collision avoidance application 115 causes drone 105 toperform are performed without human input or approval. The evasiveactions taken include, but are not limited to: increasing altitude,decreasing altitude, increasing speed, decreasing speed, changingdirection, hovering, a barrel roll, a split-s, or any other basicfighter maneuver, and/or any other suitable action. In crowded areas,multiple drones may be converging on the same point. Thus, whileperforming evasive actions, additional beacon frames from a third dronemay be received, and a new evasive action taken to avoid both otherdrones, as needed. Additionally, beacon frames may be received frommultiple sources at the same time, causing the resulting evasivemaneuvers to be more elaborate to avoid multiple drones simultaneously.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to determine if thebeacon frames are of a special type, and perform actions based on thespecial type. A special type is related to a privileged drone, such as apolice or military drone, flight instructor or regulator drone, or anyother special type. A special type may be indicated by the frequencyused to transmit the beacon frames, by a special data field in thebeacon frames, or in any other manner. In response to receiving beaconframes from a special type, the receiving drone takes specific actions.For example, if beacon frames are received from a police or militarydrone, the evasive action may be to hover or perform an autopilotlanding of the drone. Any action may be performed in response toreceiving beacon frames of a special type.

In one embodiment, collision avoidance application 115 comprises programinstructions that are programmed or configured to send feedback toremote controller 120. Optionally, upon receiving beacon frames,collision avoidance application 115 may alert the human pilot to theimpending collision by sending feedback to remote controller 120. Thefeedback may take any form. For example, force feedback may be used toallow the pilot to feel that there is an approaching drone from a givendirection. Alternatively, text, sounds, colors, lights, or othernotifications may be used. Further, feedback may be provided whenevasive actions are performed so that the human pilot knows why his orher drone performed flight maneuvers that the human pilot did notinstruct the drone to perform.

In one embodiment, a fixed object (not shown) may emit beacon frames, asdiscussed above, to ensure that drones do not hit the fixed object, orto create a “no fly zone” around the object. For example, a building mayinclude one or more radio towers that broadcast beacon frames in alldirections around the building. Any drones receiving these beacon frameswould perform evasive actions to avoid the building. The beacon framesemitted by a fixed object may include additional data that, for example,identifies a size of a no fly zone around the fixed object, such as acylindrical no fly zone extending around a fixed object with a radius of300 feet, and a height of 500 feet. Any information related to avoidinga fixed object may be included in the beacon frames sent by a fixedobject.

3. First Functional Example

FIG. 2 shows an example flowchart of a method for drone collisiondetection and avoidance. Specifically, FIG. 2 shows an example flowchartfor sending beacon frames in a current flight path of a drone. Althoughthe steps in FIG. 2 are shown in an order, the steps of FIG. 2 may beperformed in any order, and are not limited to the order shown in FIG.2. Additionally, some steps may be optional, may be performed multipletimes, and/or may be performed by different components. All steps,operations and functions of a flow diagram that are described herein areintended to indicate operations that are performed using programming ina special-purpose computer or general-purpose computer, in variousembodiments. In other words, each flow diagram in this disclosure is aguide, plan or specification of an algorithm for programming a computerto execute the functions that are described.

In step 205, a flight direction is determined. The flight direction maybe determined based on commands received from the pilot. Alternatively,or in addition, the flight direction may be determined based on sensorson the drone, such as a gyroscope, accelerometer, compass, altimeter,GPS receiver, etc. Although shown as a single step, step 205 isperformed continuously while the drone is in flight. Step 205 may beperformed at any interval, and the interval may change dynamically basedon the determined flight direction, speed, height, how crowded theairspace is, or any other factor.

In step 210, beacon frames are generated and broadcast in the flightdirection. The beacon frames may be generated in any manner, and maycontain data related to the drone broadcasting the beacon frames, suchas an identifier, flight direction information, or other data.Specifically, the beacon frames are broadcast in the flight directionusing beamforming, so that only other drones in or near the currentflight direction of the drone are warned of a potential collision. Thebeamforming may be performed in any manner now known or later developed.The beacon frames may be broadcast using any suitable frequency, such as2.4 GHz, and any suitable wireless standard. Although the 802.11wireless networking standard is discussed above, other standards mayalso be used to implement the invention. No response is needed orexpected to the beacon frames, as the beacon frames are broadcast as awarning to other drones that a drone is coming in the same direction asthe beacon frames.

In step 215, a determination is made whether there is a new flightdirection. The determination may be made in the same manner as step 205.Further, as discussed in step 205, determining a flight direction and/orif there is a new flight direction, is a continuous process while thedrone is in flight. If there is not a new flight direction, the methodproceeds to step 235. If there is a new flight direction, the methodproceeds to step 220.

In step 220, a determination is made whether the new flight direction ishovering or below a speed threshold. The speed threshold may be set toany suitable speed, and may be adjusted dynamically based on anysuitable factors. If the new flight direction is not hovering and/or isabove the speed threshold, the method proceeds to step 230. If the newflight direction is hovering or is below the speed threshold, the methodproceeds to step 225.

In step 225, broadcasting of beacon frames is ceased. The broadcastingof beacon frames is ceased in response to the drone either hovering ormoving below a speed threshold. By not broadcasting beacon frames whenhovering or moving slowly, less energy is consumed, and other drones arenot unnecessarily warned. However, even if broadcasting of beacon frameshas stopped, the drone still listens for beacon frames from otherdrones, as the drone may still need to avoid collisions, even whenhovering.

In step 230, beacon frames are broadcast in the new flight direction.The beacon frames are broadcast in the new flight direction usingbeamforming, as discussed in step 210. Optionally, the beacon frames maybe broadcast at a shorter or longer interval than in the previousdirection if, for example, the new flight direction was faster orslower, respectively, than the previous flight direction. Further, thefrequency or any other factor related to the broadcast may also changein addition to the direction of the broadcast.

In step 235, broadcasting of beacon frames in the flight directioncontinues. If the flight path has not changed, the beacon frames arecontinuously broadcast in the flight direction to continue warning otherdrones of potential collisions.

4. Second Functional Example

FIG. 3 shows an example flowchart of a method for drone collisiondetection and avoidance. Specifically, FIG. 3 shows an example flowchartfor receiving beacon frames and performing evasive action(s). Althoughthe steps in FIG. 3 are shown in an order, the steps of FIG. 3 may beperformed in any order, and are not limited to the order shown in FIG.3. Additionally, some steps may be optional, may be performed multipletimes, and/or may be performed by different components.

In step 305, beacon frames are detected from another drone. The beaconframes may be detected in any manner. Specifically, due to having MIMOantennas, each drone has a spherical detection area surrounding thedrone in which beacon frames are able to be detected/received. Anynumber of beacon frames may be received from any number of drones.Potentially, in crowded airspace a drone may be on a collision coursewith multiple other drones simultaneously.

In step 310, a direction from which the beacon frames arrived isdetermined. The direction may be determined in any manner. Specifically,the signal strength or other transmission attributes may be used todetermine the direction. Alternatively, or in addition, data within thebeacon frames may be used to determine the direction. Optionally, inresponse to detecting beacon frames and determining a direction fromwhich the beacon frames arrived, feedback may be provided to the pilot.The feedback may take any form, such as force feedback, sounds, colors,or other notifications, etc.

In step 315, a determination is made whether the beacon frames are of aspecial type. A special type of beacon frame may indicate that a police,military, or other privileged drone is sending the beacon frames, andthat special actions should be performed in response todetecting/receiving the beacon frames. If the beacon frames are not of aspecial type, the method proceeds to step 325. If the beacon frames areof a special type, the method proceeds to step 320.

In step 320, an action(s) is performed based on the special type. Eachspecial type may have a specific action associated with it. For example,if the special type is a police drone, the action may be to stop flyingand hover. Alternatively, if the special type is a military drone, thespecial action may be to disable pilot input and perform an auto-pilotlanding. Further, other data may be taken into consideration whenperforming the action, such as the direction from which the beaconframes were received, or an altitude of the drone. Any action may beperformed for any type, and the invention should not be limited to theabove examples. Further, the action is performed without input from thehuman pilot. Optionally, feedback may be sent to the pilot to alert themto the actions performed. For example, a sound or text notification maybe sent to the pilot if a police drone has been detected, informing thepilot that he or she has been “pulled over.” While the action isperformed, the drone may still monitor for beacon frames from otherdrones.

In step 325, an evasive action(s) is performed to avoid the other drone.The evasive action may be based on any available information such as acurrent altitude, speed, and/or direction of the drone, and/or onavailable information about the approaching drone, such as directionand/or speed. The evasive action may be any action including, but notlimited to: speeding up or slowing down, increasing or decreasingaltitude, any basic fighter maneuver, and/or changing direction. Whileperforming the evasive action, the drone still monitors for beaconframes from other drones. In the event that beacon frames are receivedfrom a new drone during the evasive action, the evasive action may bechanged to avoid both drones, as needed. Further, the action isperformed without input from the human pilot. Optionally, feedback maybe sent to the pilot to alert them to the actions performed, such as analert or notification.

5. Implementation Example

FIG. 4 shows an example use case for drone collision detection andavoidance. The example shown in FIG. 4 has been greatly simplified, toease understanding and, as such, the example should not be construed tolimit the disclosure to the specifics discussed below.

Turning to the example, FIG. 4 shows two drones on a potential collisioncourse, a first drone 400 and a second drone 410. Drone 400 isbroadcasting a beamformed radio signal 405. The beamformed radio signal405 contains beacon frames that are used to alert drone 410 to theimpending collision. When beacon frames from beamformed radio signal 405enter the detection area 415 of drone 410, the second drone is alertedto the presence of first drone 400, and that there is an imminentpotential collision. Detection area 415 is a spherical space arounddrone 410 in which that drone is able to detect/receive radio signals,such as beacon frames. Drone 410 is able to determine the direction fromwhich the beacon frames have been received using signal strength or anyother method. And, because the beacon frames were sent usingbeamforming, drone 410 therefore knows the direction in which drone 400is approaching. Accordingly, drone 410 is able to take evasive action byincreasing flight altitude, and avoid the collision with drone 400.

Although not shown in FIG. 4, drone 400 has a spherical detection areasimilar to detection area 415, so that drone 400 can detect beaconframes from approaching drones and take evasive action as needed.Likewise, although not shown in FIG. 4, drone 410 also broadcasts abeamformed radio signal containing beacon frames to alert other dronesthat drone 410 is approaching. As discussed above, the inventionfunctions similar to headlights on a car. Other drones are able to “see”where a drone is headed, and the other drones must take evasive actionto avoid a collision. Simultaneously, the other drones are alsobroadcasting where they are going so that still other drones may avoidthem.

This invention has many advantages over other methods of drone collisiondetection and avoidance. One advantage, is that the present inventionoperates using standard equipment on drones—the ability to send andreceive wireless signals, such as Wi-Fi, although other signal types maybe used. No complicated or energy consuming radar or other methods areused. Further, the present invention does not require the drone sendingsignals to know where other drones are, or to receive any data fromother drones. Rather, the impetus is on any drones receiving a signal tomove out of the way of a potential collision. This results in a fast andefficient method for drone collision detection and avoidance.Optionally, a connection may be established between nearby drones toexchange data. Additionally, because signals are only sent in the flightdirection of drones, less energy is used than if signals needed to bebroadcast in all directions. Additional energy savings may be had byceasing broadcasting of beacon frames when the drone is hovering ormoving slowly.

6. Hardware Overview

According to one embodiment, the techniques described herein areimplemented by one or more special-purpose computing devices. Thespecial-purpose computing devices may be hard-wired to perform thetechniques, or may include digital electronic devices such as one ormore application-specific integrated circuits (ASICs) or fieldprogrammable gate arrays (FPGAs) that are persistently programmed toperform the techniques, or may include one or more general purposehardware processors programmed to perform the techniques pursuant toprogram instructions in firmware, memory, other storage, or acombination. Such special-purpose computing devices may also combinecustom hard-wired logic, ASICs, or FPGAs with custom programming toaccomplish the techniques. The special-purpose computing devices may bedesktop computer systems, portable computer systems, handheld devices,networking devices or any other device that incorporates hard-wiredand/or program logic to implement the techniques.

For example, FIG. 5 is a block diagram that illustrates a computersystem 500 upon which an embodiment of the invention may be implemented.Computer system 500 includes a bus 502 or other communication mechanismfor communicating information, and a hardware processor 504 coupled withbus 502 for processing information. Hardware processor 504 may be, forexample, a general purpose microprocessor.

Computer system 500 also includes a main memory 506, such as a randomaccess memory (RAM) or other dynamic storage device, coupled to bus 502for storing information and instructions to be executed by processor504. Main memory 506 also may be used for storing temporary variables orother intermediate information during execution of instructions to beexecuted by processor 504. Such instructions, when stored innon-transitory storage media accessible to processor 504, rendercomputer system 500 into a special-purpose machine that is customized toperform the operations specified in the instructions.

Computer system 500 further includes a read only memory (ROM) 508 orother static storage device coupled to bus 502 for storing staticinformation and instructions for processor 504. A storage device 510,such as a magnetic disk or optical disk, is provided and coupled to bus502 for storing information and instructions.

Computer system 500 may be coupled via bus 502 to a display 512, such asa cathode ray tube (CRT), for displaying information to a computer user.An input device 514, including alphanumeric and other keys, is coupledto bus 502 for communicating information and command selections toprocessor 504. Another type of user input device is cursor control 516,such as a mouse, a trackball, or cursor direction keys for communicatingdirection information and command selections to processor 504 and forcontrolling cursor movement on display 512. This input device typicallyhas two degrees of freedom in two axes, a first axis (e.g., x) and asecond axis (e.g., y), that allows the device to specify positions in aplane.

Computer system 500 may implement the techniques described herein usingcustomized hard-wired logic, one or more ASICs or FPGAs, firmware and/orprogram logic which in combination with the computer system causes orprograms computer system 500 to be a special-purpose machine. Accordingto one embodiment, the techniques herein are performed by computersystem 500 in response to processor 504 executing one or more sequencesof one or more instructions contained in main memory 506. Suchinstructions may be read into main memory 506 from another storagemedium, such as storage device 510. Execution of the sequences ofinstructions contained in main memory 506 causes processor 504 toperform the process steps described herein. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions.

The term “storage media” as used herein refers to any non-transitorymedia that store data and/or instructions that cause a machine tooperation in a specific fashion. Such storage media may comprisenon-volatile media and/or volatile media. Non-volatile media includes,for example, optical or magnetic disks, such as storage device 510.Volatile media includes dynamic memory, such as main memory 506. Commonforms of storage media include, for example, a floppy disk, a flexibledisk, hard disk, solid state drive, magnetic tape, or any other magneticdata storage medium, a CD-ROM, any other optical data storage medium,any physical medium with patterns of holes, a RAM, a PROM, and EPROM, aFLASH-EPROM, NVRAM, any other memory chip or cartridge.

Storage media is distinct from but may be used in conjunction withtransmission media. Transmission media participates in transferringinformation between storage media. For example, transmission mediaincludes coaxial cables, copper wire and fiber optics, including thewires that comprise bus 502. Transmission media can also take the formof acoustic or light waves, such as those generated during radio-waveand infra-red data communications.

Various forms of media may be involved in carrying one or more sequencesof one or more instructions to processor 504 for execution. For example,the instructions may initially be carried on a magnetic disk or solidstate drive of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to computer system 500 canreceive the data on the telephone line and use an infra-red transmitterto convert the data to an infra-red signal. An infra-red detector canreceive the data carried in the infra-red signal and appropriatecircuitry can place the data on bus 502. Bus 502 carries the data tomain memory 506, from which processor 504 retrieves and executes theinstructions. The instructions received by main memory 506 mayoptionally be stored on storage device 510 either before or afterexecution by processor 504.

Computer system 500 also includes a communication interface 518 coupledto bus 502. Communication interface 518 provides a two-way datacommunication coupling to a network link 520 that is connected to alocal network 522. For example, communication interface 518 may be anintegrated services digital network (ISDN) card, cable modem, satellitemodem, or a modem to provide a data communication connection to acorresponding type of telephone line. As another example, communicationinterface 518 may be a local area network (LAN) card to provide a datacommunication connection to a compatible LAN. Wireless links may also beimplemented. In any such implementation, communication interface 518sends and receives electrical, electromagnetic or optical signals thatcarry digital data streams representing various types of information.

Network link 520 typically provides data communication through one ormore networks to other data devices. For example, network link 520 mayprovide a connection through local network 522 to a host computer 524 orto data equipment operated by an Internet Service Provider (ISP) 526.ISP 526 in turn provides data communication services through the worldwide packet data communication network now commonly referred to as the“Internet” 528. Local network 522 and Internet 528 both use electrical,electromagnetic or optical signals that carry digital data streams. Thesignals through the various networks and the signals on network link 520and through communication interface 518, which carry the digital data toand from computer system 500, are example forms of transmission media.

Computer system 500 can send messages and receive data, includingprogram code, through the network(s), network link 520 and communicationinterface 518. In the Internet example, a server 530 might transmit arequested code for an application program through Internet 528, ISP 526,local network 522 and communication interface 518.

The received code may be executed by processor 504 as it is received,and/or stored in storage device 510, or other non-volatile storage forlater execution.

7. Extensions and Alternatives

The process described herein of determining flow length characteristicsusing a network infrastructure device, and the process of using acollector device to analyze the flow length characteristics and takeresponsive action, may be implemented independently or in combination.For example, when an independent approach is used, the collector devicemay be programmed to perform: receiving, at the collector device, afirst length of a first datagram, a second length of a second datagram,and a duration between a first arrival of the first datagram and asecond arrival of the second datagram; determining, using the firstlength, second length, and duration, an application associated with thefirst datagram and the second datagram; in response to determining thatthe application is a known malicious application, sending an alert;wherein the method is executed by one or more computing devices. In oneapproach, determining the application further comprises using a trainedclassifier, wherein the trained classifier is trained on training datafrom a software application reporting a name and a hash for the softwareapplication associated with a flow. The collector device may beprogrammed for accessing a file reputation service determine areputation of the application. In some embodiments the application is aclient application. In one approach, determining the application isperformed in retrospect to detect a malicious application that wasunknown when the first length, the second length, and the duration werereceived.

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense. The sole and exclusive indicator of the scope of the invention,and what is intended by the applicants to be the scope of the invention,is the literal and equivalent scope of the set of claims that issue fromthis application, in the specific form in which such claims issue,including any subsequent correction.

What is claimed is:
 1. A system comprising: one or more processors; anelectronic digital memory storing one or more sequences of instructionswhich, when executed by the one or more processors, cause the one ormore processors to perform: determining a flight direction valueassociated with a direction of flight of a first drone that is equippedwith multiple-input and multiple-output (MIMO) antennas; causingbroadcasting, on a radio frequency and in the direction of flight basedon the flight direction value, a beamformed signal comprising aplurality of first beacon frames; determining a new flight directionvalue of the same first drone and associated with a new direction offlight of the first drone; in response to the new flight directionvalue, causing broadcasting of the plurality of first beacon framesusing the new flight direction based on the new flight direction value;detecting one or more second beacon frames from a second drone and asecond direction value associated with a second direction from which theone or more second beacon frames are arriving; in response to detectingthe one or more second beacon frames, causing the first drone toperform, without input from a pilot of the first drone, and based on thesecond direction value, one or more of a change in elevation, heading,speed, or type of operation, directed toward causing the first drone tofollow a flight path that is separated from the second drone.
 2. Thesystem of claim 1, wherein each of the plurality of first beacon framescomprises an identifier for the first drone.
 3. The system of claim 1,wherein the radio frequency is an Industrial Scientific Medical (ISM)band.
 4. The system of claim 3, wherein the ISM band is 802.11 forwireless networking.
 5. The system of claim 1, further comprisinginstructions which when executed by the one or more processors causeceasing broadcasting the plurality of first beacon frames when the newflight direction is stationary or below a threshold speed.
 6. The systemof claim 1, wherein the one or more second beacon frames indicate thesecond drone is of a special type; further comprising instructions whichwhen executed by the one or more processors cause performing the one ormore of the change in elevation, heading and type of operation based onthe special type.
 7. The system of claim 6, further comprisinginstructions which when executed by the one or more processors cause thefirst drone to hover.
 8. The system of claim 1, further comprisinginstructions which when executed by the one or more processors cause:detecting one or more third beacon frames from a third drone, and athird direction value associated with a third direction from which theone or more third beacon frames are arriving; in response to detectingthe one or more second beacon frames and the one or more third beaconframes, causing the first drone to perform, without input from a pilotof the first drone, and based on the second direction value and thethird direction value, one or more of a change in elevation, heading ortype of operation, directed toward causing the first drone to follow aflight path that is separated from the second drone and the third drone.9. The system of claim 1, further comprising instructions which whenexecuted by the one or more processors cause, in response to detectingthe one or more beacon frames from the second drone, sending feedback tothe pilot of the first drone.
 10. The system of claim 1, furthercomprising instructions which when executed by the one or moreprocessors cause connecting to the second drone using data from the oneor more beacon frames.
 11. The system of claim 1 comprising a computerin the first drone.
 12. A method comprising: determining a flightdirection value associated with a direction of flight of a drone that isequipped with multiple-input and multiple-output (MIMO) antennas;causing broadcasting, on a radio frequency and in the direction offlight based on the flight direction value, a beamformed signalcomprising a plurality of beacon frames; determining a new flightdirection value of the drone and associated with a new direction offlight of the drone; in response to the new flight direction value,causing broadcasting of the plurality of beacon frames using the newflight direction based on the new flight direction value.
 13. The methodof claim 12, wherein each of the plurality of beacon frames comprises anidentifier for the drone.
 14. The method of claim 12, wherein the radiofrequency is an Industrial Scientific Medical (ISM) band, and whereinthe ISM band is 802.11 for wireless networking.
 15. The method of claim12, further comprising: ceasing broadcasting the plurality of beaconframes when the new flight direction is stationary or below a thresholdspeed.
 16. A method comprising: detecting, by a first drone, one or morebeacon frames from a second drone and a direction value associated witha direction from which the one or more beacon frames are arriving; inresponse to detecting the one or more beacon frames, causing the firstdrone to perform, without input from a pilot of the first drone, andbased on the direction value, one or more of a change in elevation,heading, speed, or type of operation, directed toward causing the firstdrone to follow a flight path that is separated from the second drone.17. The method of claim 16, wherein the one or more beacon framesindicate the second drone is of a special type; and further comprising:performing the one or more of the change in elevation, heading and typeof operation based on the special type.
 18. The method of claim 16,further comprising causing the first drone to hover.
 19. The method ofclaim 16, further comprising: in response to detecting the one or morebeacon frames from the second drone, sending feedback to the pilot ofthe first drone.
 20. The method of claim 16, further comprising:connecting to the second drone using data from the one or more beaconframes.